To prevent loss of personal data, many technologies provide cloud backup services, that is, personal data of a user is uploaded and backed up to storage of a cloud; in the case of device replacement, the user can easily recover a working or use environment from the cloud backups; some cloud backup technologies can even cover applications installed on the device.
In many cases, a device of the user cannot be used because the user currently does not have the device or a temporary failure (such as power-off/arrears/technical failure) occurs, and at this time, if there are some urgent tasks to be processed, it is natural to think of borrowing a device of another around. However, general tasks rely on user data and the data is not stored in the device of others; because full backups of the user may often be up to tens of gigabytes (G), and most of the data may not be required for the user to complete the urgent tasks, it will be laborious to completely establish a virtual device from the cloud backups.